The invention relates to a spraying head according to the preamble of claim 1, especially to a spraying head intended for fire extinguishing, which comprises a frame part, an inlet for extinguishing medium and at least two nozzles.
The invention also relates to a method for fire extinguishing according to the preamble of claim 10.
The invention also relates to a spraying apparatus according to claim 19.
In fire extinguishing technique, it is advantageous that a fire to be extinguished is detected in time. Then, the volume of extinguishing medium required for extinguishing the fire is small compared with a situation in which the fire has been able to become large. Furthermore, it is advantageous if the largest volume of extinguishing medium can be directed at the fire site itself or its immediate vicinity.
Sprinklers are known in fire extinguishing technique in connection with extinguishing systems which sprinklers comprise a triggering means after the activation (triggering) of which, e.g. from the effect of heat, a passage for extinguishing medium is opened to sprinkler nozzles. When the sprinkler is non-active, the triggering element has not triggered, the passage to the nozzles stays closed and the sprinkler does not spray extinguishing medium. On the other hand, also open spraying heads are known in connection with extinguishing systems which do not comprise a triggering means, but they spray extinguishing medium immediately after the passage of extinguishing medium to the inlet of the nozzle head is open.
In an open nozzle system (so-called “Deluge” system), extinguishing medium is conveyed to the feed pipe of the spraying head when a signal of a fire has been received from a fire detector. The spraying heads of the system in question are open spraying heads which start to spray extinguishing medium immediately when it is conveyed to them along a medium pipe. In the system, open spraying heads spray extinguishing medium for the whole area of the system or, in a system comprising several protection areas, to a certain sub-area. Open nozzle systems are typically dimensioned to confine or extinguish sizeable fires, whereby the volume of extinguishing medium to be sprayed can also be rather large and many times extinguishing medium is conveyed to wrong areas from the viewpoint of protection. With conventional fire-extinguishing systems using large volumes of extinguishing medium, the disadvantage is emphasised, but also, with extinguishing systems based on water mist using considerably smaller volume of water, the excess spraying of extinguishing medium can be harmful, especially on sites where there are electronic devices or on sites having high hygiene requirements.
In fire extinguishing arrangements utilising sole sprinklers, closed when non-active, extinguishing medium is exclusively sprayed by activated sprinklers. Then, extinguishing output can be directed better, exactly at the fire site. However, the sprinkler is not activated until the fire has become quite large, whereby the required local volume of water is also great.
Also so-called mixed systems are known in which there are separate open spraying heads and separate sprinkler heads closed when non-activated in a certain area, e.g. arranged alternately into connection with an extinguishing medium pipe. Then, open nozzles produce an adequate volume of water for controlling relatively small fires, but if the fire has become large before the system is activated or if the fire develops very fast, the sprinkler nozzles start to trigger from the effect of heat at the fire site. The arrangement in question can be awkward from the viewpoint of installation, because the spraying heads are different from each other.
The object of this invention is to achieve a totally new arrangement by means of which fire extinguishing can be taken on already at such an early stage that the used volume of water will remain minimal, but which also has a capacity to control a larger fire, if required.